staging: rts_pstor: use #ifdef instead of #if

This patch fixes a number of the following warnings:
warning: "CONFIG_RTS_PSTOR_DEBUG" is not defined

The code uses '#if CONFIG_RTS_PSTOR_DEBUG' when it should be using '#ifdef'

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>